To investigate the role of the PPP in PD, we first detected expression and activity of G6PD, the rate-limiting enzyme of the PPP, in four in vivo mouse PD models generated by an intranigral or intraperitoneal injection of LPS, daily subcutaneous injection of MPTP for 6 days, or transgenic overexpression of A53T mutant α-synuclein. This evidence concerns the gene G6PD and Parkinson disease.